Question

why are currents called warm or cold​

Answer 1

Answer:

Those currents that flow from the Equator towards the poles are warmer than the surrounding water and so they are called warm currents. The ocean currents that flow from the polar areas towards the Equator are cooler compared to the surrounding water, so they are called cold currents.

Answer 2

Answer:

Differences in water density, resulting from the variability of water temperature (thermo) and salinity (haline), also cause ocean currents. This process is known as thermohaline circulation. In cold regions, such as the North Atlantic Ocean, ocean water loses heat to the atmosphere and becomes cold and dense.